Combine the flours and yeast in a large bowl. Add the water and oil; mix with your fingers just until combined smoothly. The dough will be wet and sticky. Cover the bowl with plastic and let rest for 15 to 20 minutes. After this rest (called an autolyse), mix in the salt.
Knead on an unfloured work surface. To knead, squeeze the dough vigorously between the thumbs and index fingers of both hands. Move along the length of the dough, squeezing hard enough to make holes where your thumbs and fingers meet. The dough will be sticky, but don't add flour -- use a dough scraper instead. Flip and repeat, squeezing along its length. Continue squeezing and flipping for 5 to 10 more minutes. Ideally the dough will come together and feel smooth, but if it's still sticky, don't worry -- the texture will improve during fermentation. Transfer to an unoiled bowl and cover with plastic.
After 30 minutes, lightly flour the dough's top and the work surface and then turn the dough out of the bowl. Gently spread the dough to flatten it but not to completely deflate it. Fold the dough into a tight square package, folding top down, side over, bottom up, and side over as you'd fold a handkerchief. Return it to the rising bowl, covered with plastic, for 30 minutes. Repeat this flattening, flouring, and folding. Let the dough ferment for 2 to 3 more hours, until doubled in volume and full of large bubbles. It should spring back when you press it.
Pull the dough out of the bowl, flour it well, and tuck the edges in to make a smooth package. Don't pop the bubbles, but do tighten. Flour, cover with plastic, and let rest for 10 to 15 minutes.
With floured hands, gently press and stretch the dough into a 10x6-inch rectangle that's a scant inch thick. Transfer to a sheet of floured parchment. Flour the dough again.
With a slender, floured rolling pin, roll out one-quarter of the long side of the dough, making a thin flap to cover the thicker, unrolled portion of the dough when folded over. Press with the rolling pin where the thin sheet joins the dough to make a sharp demarcation. If needed, use more flour to keep the dough from sticking. Moisten the thick half of the dough with water. Dip the herb leaves in water (shake off excess droplets) and arrange them on the thick portion of the dough. It's okay to crowd the leaves a little (they'll spread a bit after rolling), but don't overlap them. Fold over the thin sheet of dough to cover the herb leaves completely. Tuck the edges under and pat gently to push out any air bubbles. Starting from the short end, roll lightly with a floured rolling pin until the herbs come into sharp relief but have not popped through and the trapped air is expelled. Be gentle during rolling, even though you'll end up deflating the dough, and aim for an even shape.
Sprinkle flour on the dough and cover with plastic. Let proof until thicker and puffy, about 2 hours. To test, press the dough: the indentation should fill in slowly. An hour before the end of the proof, put a baking stone in the top third of the oven; heat the oven to 450°F.
When the dough is fully proofed, brush off the flour with a dry pastry brush and then smear with a thin layer of olive oil (about 1 tablespoon). Dimple the loaf all over with your fingers, poking in between the herb leaves, pushing down to the bottom of the dough without breaking through. Sprinkle with coarse salt. Transfer the parchment and dough to the hot baking stone. Bake the dough on the parchment until deep golden all over, about 15 minutes, rotating after 10 minutes. The parchment will darken in the oven, but it won't catch fire. Transfer the bread to a rack and enjoy soon: it's best still warm.